Protective arrangement for highpower electronic tubes



y 5, 1950 s. v. JENNINGS 2,516,215

PROTECTIVE ARRANGEMENT FOR HIGH-POWER ELECTRONIC TUBES Filed June 23, 1948 5 Sheets-Sheet l 32 43 x/ )4 HQ 4 d 42 I:

INVENTOR. SHELDON V. JENNINGS 2s By 36 Q ATTORNEYS July 1950 s. v. JENNINGS 2,516,215

PROTECTIVE ARRANGEMENT FOR HIGH-POWER ELECTRONIC TUBES Filed June 25, 1948 3 Sheets-Sheet 2 II--i II 29 55 56 57 m m l9 l9 33 39 55 E I 2| H 35 INVENTOR. SHELDON v. JENNlNGS ATTORN EYS July 25, 1950 s. v. JENNINGS 2,516,215

PROTECTIVE ARRANGEMENT FOR HIGH-POWER ELECTRONIC TUBES Fil ed .June 25, 1948 s Sheets-Sheet 5 IN VEN TOR.

SHELDON V. JENNINGS ATTORNEYS Patented July 25, 1950 PROTECTIVE ARRANGEMENT FOR HIGH- POWER ELECTRONIC TUBES Sheldon V. Jennings, New Albany, Ind., assignor to The Girdler Corporation, Louisville, Ky, a

corporation of Delaware Application June 23, 1948, Serial No. 34,785

14 Claims.

This invention relates to protective arrange ments for high-power electronic tubes such as used, for example, in high-frequency dielectric heating systems.

In accordance with one aspect of the invention, a high-power electronic tube is mounted with its cooling fins in a sleeve or equivalent housing and a vane supported in the path of cooling air discharged from the sleeve responds to predetermined decreased air flow to efiect actuation of a switch which may be used to interrupt supply of current to the tube: more specifically, the tube when of the type having cooling fins and a glass envelope at its opposite ends is so mounted that air discharged from the aforesaid sleeve flows over the glass envelope and the control vane is so shaped and located that it more or less completely encircles the neck of the tube between the cooling fins and envelope.

Further in accordance with the invention, the tube may be disposed in a shield compartment with other associated radio-frequency components also cooled by air supplied to the compartment by a duct terminating short of the sleeve of the tube-mount. Preferably, the aforesaid switch is disposed externally of the shield compartment and is actuated by a mechanical connection extending through a compartment wall to the pivoted vane.

The invention also resides in features of con struction, combination and arrangement hereinafter described and claimed.

For a more detailed understanding of the invention and for illustration of embodiments thereof, reference is made to the accompanying drawings in which:

Fig. 1 is a front elevational view of certain components of a high-frequency dielectric heating unit including its power-tube and associated cooling apparatus;

Fig. 2 is a plan view, on enlarged scale, or" the tube-mount and the air-flow vane shown in Fig.

Fig. 5 is a side elevational view, partly-in section, of the tube-mount and a modification of the associated air-flow switch; and.

Fig. 6 is an exploded view of the air-flow vane and associated parts shown in Fig. 5.,

Referring to Fig. 1, the. blower I0 isdisposed in a compartment I I of a cabinet or housing having frame members I2. Air entering the blower intake I3 is discharged through the outlet duct I4 of the blower into a shielded compartment I5 of the housing in part defined by the partition or wall structure it. The tube-mount ll is disposed in shielded compartment It with its sleeve I8 in alignment with and spaced over the airdischarge opening in the lower wall of compartment I5. The extensions IQ of the tube-mount I! are supported by stand-ofi insulators 2B which are spaced around the air opening in partition H5 and arepreferably provided with corona shields 2!, Figs. 1 and 3.

The power tube 22 is mounted in position with its finned anode 23 slidably received by the sleeve [8 of the tube-mount H, as shown in Figs. 2- and 3, the glass envelope 2A of the tube, broken away in Figs. 2 and 3, extending above the tube-mount as shown in Fig. 1. The tube-mount I! may be a light metal casting so that it assists in conduction of heat from the tube anode.

A substantial proportion of the air discharged from duct I4 into compartment I5 enters the lower .end of sleeve I8 and flows upwardly through it in passages defined by the coolingfins of the tube anode (see Figs. 2 and 5) thus to prevent the anode temperature from exceeding a safe operating value. The air leaving the upper end of the sleeve I8 in substantial part flows over the glass envelope 24 of the tube and the terminal seals at the upper end thereof. Air discharged from duct I4 which does not enter the sleeve, as well as the air discharged from the sleeve I8, circulates in turbulent manner in the compartment I5 and serves to cool other radio-frequency components such as chokes, resistors and the like, generically exemplified by resistor 25. The air leaves the shield compartment I5 through louvres or vents not shown.

Particularly in dielectric heating systems, the oscillator tubes or power tubes are subjected to severe operating conditions which make it imperative that supply of current to the tube be promptly interrupted or reduced if the flow of cooling air falls below a safe minimum value. In the arrangement as thus far described, even though blower I0 may be supplying the normal amount of cooling air to the shielded compartment I5, cooling of the anode of the tube or of the glass envelope may be inadequate or localized due to collection of dust or other foreign material between the anode fins so clogging or partially obstructing at least some of the airflow channels within sleeve I8. To protect the tube in such event, or upon occurrence of inadequate supply of cooling air due to any other cause, there is provided an air-flow device which in response to decrease of the air discharged from tube-mount sleeve I8 reduces or interrupts supply of anode current to tube 22.

In the particular embodiments herein shown, the air-flow device 26 comprises a switch unit 21 disposed externally of the shielded compartment IS, an insulating actuator rod 28 extending through the partition I 6 of the compartment'and a pivoted vane 29 which is connected to rod 2-8 and encircles the neck of tube 22 above its finned anode 23 and below its glass envelope 22. The weights 3% are so adjusted or positioned on vane 29 that for normal discharge of air from sleeve IS, the vane is tilted slightly upwardly'to hold the actuator rod 28 in position maintaining the contacts of switch-unit 2! in position insuring continued or normal supply of current to tube 22.

Whether these contacts are normally open or normally closed will depend upon the associated relay or control arrangement; for brevity, it will be assumed that the contacts are normally open.

When for any reason, the "air which is passed from the finned anode falls below the selected minimum rate of supply, the biasing weights 3E1 cause the vane 29 to swing downwardly, so lifting the actuator rod 28 and permitting or causing the switch contacts to move to position resulting, for example, in interruption of further supply of current to the tube 22.

In the particular construction shown in Figs.

2 to 4, the vane 29 comprises two substantially semi-circular members 3! each pivotally mounted as by a rivet or screw32 to a channel block 33, or equivalent, which is pivotally mounted as by .a pin '34 to an L bracket ,or support 35. Preferably, as most clearly shown in Fig. 4, the bracket 35 is detachably connected to the sleeve N3 of the tube-mount IT. The clamping bolt 36 therefor may extend throughbracket 35 and threadably engage the sleeve I'B, the head of the bolt or thunmbscrew 36 being suitably shaped to facilitate manual removal. The pair of screws 3! which threadably engage the bracket 35 extend therefrom into closely fitting unthreaded holes in the sleeve l8 and so serve as positioning pins.

To facilitate attainment of the desired positional relations between the vane 29 and the movable switch contact of unit 21, the actuating rod 28 is extendable or of adjustable length. Specifically, there is provided a threaded member 38 which serves as the upper part ofthe actuator rod 28 and which is pivotally connected, as by pivot pin 39, to the channel block 33. The member 38 and rod 28 are interconnected by a threaded turnbuckle rod 40 which permits adjustment of the effective length of rod 28. When the desired relation has been obtained, the lock nuts 4! are tightened to maintain the parts in the desired relative position. Preferably, and as shown in Figs. 1, 3 and 5, the lower end of the actuator rod 28 merely rests upon and is not rigidly connectedto the contact-operating member 9 of the switch unit '21.

The two halves 3| of vane 29 are normally held in the relative position shown in Fig. 2 by a cross-bar 42 having a slot through which extend the pins or rivets 43 respectively fastened to each half 3| of the vane. The frictional engagement between the cross-bar 42, the members 3| and the heads of pins 43 is sufficient to hold the two halves 3| of the vane 29 so that they substantially encircle the neck of the tube in the path of the air leaving sleeve l8. When it is desired to replace the tube 22, the two halves 3i of the vane are moved apart, each pivoting about its pin 32, thus to afford sufficient clearance for withdrawal of one tube and insertion of another. With the vane members 3! moved apart for this purpose, the pins 43 engage the ends of the slot in the cross-piece 42 to limit the extent of separation of members 3!. After replacement of the tube, the vane halves 3| are pushed toward one another to their original positions again to encircle the neck of the tube 22 to be protected from inadequate cooling.

It should be noted replacement of the tube is effected without disturbance of the settings of the actuator rod or the biasing weights.

.In the generally similar air-flow device shown in Figs. 5 and 6, the elements corresponding with those shown in Figs. 2 to 4 are identified by the same reference characters, in some instances with addition of a sufiix letter. Accordingly, it is unnecessary in detail to describe this modification and for brevity the discussion thereof is confined to distinguishing features.

The air fiow vane in Figs. 5 and 6, is a single annularmember 29A which is circumferentially continuous except for a gap 44 suifioient to clear the neck of tube 22. The shank 45 of vane 29A is provided with a pair of keyhole slots 46. The screws 4"! extend through slots 46 and into threaded holes at! of the channel block 33A normally to clamp the vane 29A to the block in position overlying the finned anode 23 0f the tube, Fig. 5. When it is desired to remove tube 22, the screws 41 are loosened to permit the vane 29A to be slid along to block 33A to position for which the heads of the screws can pass through the enlarged ends of the keyhole slots 45, 46, in the vane 29A. The vane may then, without disturbing the setting of .its biasing weights 30A, be removed from the block and pulled clear of the tube 22 to allow removal thereof from its mount ll. Upon replacement of the tube, the reverse procedure is effected; .i. e., the vane 29A is'slipped around the neck ofthe tube, dropped over the heads of screws 4'! onto block 33A and then pushed forwardly so that the heads of the screws 41 overlie the narrow portions of the keyhole slots. The screws 41, 4'! are then re-tightened and the device is in readiness for resumption of its normal functioning. It should be noted that as in Figs. 2 to 4, the replacement of the tube is effected without disturbing the adjustment of the actuator rod between the switch contacts and the vane mount or the setting of the bias weights. It should be further noted the end of shank 45 of vane 29A is turned up or otherwise so shaped that it is impossible to replace vane 29A in any position except the proper original position.

In the modification shown in Figs. 5 and 6, enhanced sensitivity is obtained by use of needlepoint pivots for the channel block 33A and for the member 38A of the actuator rod 23. Specifically, the channel block 33A is pivotally mounted upon the bracket 35A by a pair of pointed pivot members 34A which are threadably received by opposite sides of the channel block and extend into conical bearing depressions 49 in opposite sides of the bearing extension 50 of the bracket 35A. The needle pivots 34A are locked in adjusted position by nuts 5! or equivalent.

In like manner, the needle pivots 39A are threadably received by the opposite sides of channel member 33A and extend .into conical bearing depressions '52 in the upper end of rod member 5.. 38A, the lock nuts 53 retaining the pivot pins 39A in their adjusted position. i

In both modifications, the bearing extension 50 is so designed that it forms a stop 58 which prevents the channel block (33 or 33A) from tilting far enough to allow the vane (29 or 29A) to strike the glass envelope 24 of the tube.

In both modifications, and as illustrated in Fig. 3, the tube-mount I! is resiliently supported from the stand-off insulators 20 for limited rela-, tive movement so to protect the tube and its elements from injury in event of mechanical shock or vibration of the frame [2 of the equipment. By attaching the mounting bracket ;(35 or 35A) for the air-flow vane and the actuator rod 28 to the resiliently-supported tube-mount and leaving the rod 28 without rigid coupling to the contact system of the switch unit 21, the position of vane (29 or 29A) is not affected by ordinary shock or vibration conditions and responds only to predetermined decrease in airdischarge from sleeve [8 of the tube-mount. The possibility of accidental shut-down of the tube is therefore minimized. The principal advantage of absence of a rigid connection between the switch unit and the actuator rod is that it facilitates mechanical assembly of the air-flow device as the alignment is not critical.

Any suitable type of shock-mount may be interposed between each of the stand-oil insulators and the tube-mount; in the particular type shown in Fig. 3, a resilient plate or diaphragm 54 is fastened, as by screws 55, about its perimeter to the underside of the associated mount extension IS. The diaphragm 54 is perforated for extension therethrough of the stud 56 from the upper end of the stand-off insulator. The nuts 51, or equivalent, clamp between them the central portion of the diaphragm 54 and so anchor it to the stud 56.

Also in both modifications and as shown in Figs. 1, 3 and 5, the switch unit 21 is located externally of the shield compartment 15 to prevent any of the high-power high-frequency radiation from the tube or its associated high-frequency circuit components from being picked up by the switch leads and by them conducted or re-radiated to cause interference to reception of radio signals. Specifically the switch unit 21 is mounted upon a bracket 60 fastened as by bolts 59 to the underface of shield partition I6 with the contact-operating member 9 disposed below the opening in partition l6 through which the actuator rod 28 extends. As evident from the disclosure, the switch unit may be installed or replaced without disturbing the mounting of the vane or the actuating rod, and, conversely, the assembly comprising the vane, the actuating rod and their mounting bracket may be installed or replaced without disturbing the switch unit 21.

More than one tube may be supplied with cooling air from blower In, or equivalent, in which case each tube will be mounted generally as shown in Fig. 1 with the sleeve of the tube-mount over an air-discharge opening of the blower duct I4 or extension thereof. Each tube is protected by its associated air-flow device calibrated or adjusted in accordance with the air requirements of the particular tube. Whether one or more tubes are so supplied with air, leaks in the air duct or manifold do not lessen the protection afiorded by the control switch of the present invention when positioned as above described. This is an important advantage over air-flow switches located in the air-duct because they may be rendered inefiective by air leaks which may arise because of high-voltage arcs, loosening of airline connectors due to vibration and other causes arising under operating conditions of high-frequency heating equipment.

Although the particular illustrated disposition of the tube and tube-mount is preferred for very high-power tubes, it is generally feasible with tubes of the type shown to mount them either with the glass-end beyond the vane in the direction of air-flow or with the glass-end in advance of sleeve l8 of the tube-mount in the direction 01' air flow. The invention is also applicable to other types of high-power tubes including those ha ing the cooling fins intermediate the ends, those having cooling fins at the ends with an intermediate glass envelope, and those having disk fins with air flow at right angles to the axis of the tube. In all cases, whether or not the air flows over the glass envelope, the vane for actuating the control switch is disposed in the path of air discharged from an enclosure for the cooling fins, or equivalent radiator structure, of the tube.

It shall be understood the invention is not limited to the arrangementsspecifically disclosed for purpose of illustration and that changes may be made within the scope of the appended claims.

What is claimed is:

1. An arrangement for preventing overheating of an electronic tube of the type having cooling fins which comprises a tube-mount having a sleeve for receiving said cooling fins, structure having an opening for discharge of cooling air, means for supporting said tube-mount with said sleeve spaced from said opening in position to receive air discharged therefrom, a movable vane in the path of air discharged from said sleeve, after passage over said fins, and a switch actuated by said vane in response to changes in fiow of discharge air from said sleeve.

2. An arrangement for preventing overheating of an electronic tube of the type having cooling fins which comprises structure for directing cooling air over said cooling fins, a movable vane in the path of air discharged from said structure after passage over said fins, a switch, and a mechanical connection between said vane and said switch for actuation of said switch when the air discharged from said structure falls below a predetermined minimum.

3. An arrangement for preventing overheating of an electronic tube having a finned anode at one end and a glass envelope at the other end comprising tructure for directing cooling air over said finned anode and thence over the glass envelope, a movable vane mounted to encircle the tube'between its finned anode and its glass envelope in the path of said cooling air after passage over said finned anode, a switch, and a mechanical connection between said vane and said switch for actuation of said switch when the air flow from said anode to said envelope falls below a predetermined minimum.

4. An arrangement for preventing overheating of an electronic tube having cooling fins comprising a tube-mount having a sleeve for receiving said cooling fins, a vane pivotally supported on said tube-mount in the path of air discharged from said sleeve after passage over said cooling fins, and switch means coupled to said vane for actuation thereby in response to decreased discharge of air from said sleeve.

5. An arrangement for preventing overheating of an electronic tube having a finned anode and a glass envelope at opposite ends thereof comprisingv a tube mount' having a sleeve for receiv ing"the finned anode of said tube and positioning the glass envelope thereof, a vane "pivotally supported on said tube-mount and encircling the mounted tube intermediate its ends to respond to-flow of air from said sleeve toward said glass envelope, and switch means coupled to said vane for actuation therebyin response to decreased discharge of air from-said sleeve toward said tube envelope. -6. An arrangement for preventing overheating of an electronic tube having a finned anode and a :glass envelope respectively at opposite ends thereof comprising a tube-mount having a sleeve for 'receiving 'the finned anode of said tube and positioning the glass envelope thereof, a member pivotally supported on said tube-mount out of the path of insertion and withdrawal of said tube, and a vane attached to said member normally to encircle the mounted tube in the path of a'ir from said sleeve toward the glass envelope and movable relatively to said member to permit insertion or withdrawal of the tube.

7. An arrangement for preventing overheating of high-frequency circuit components including an electronic tube which comprises a compartment for said circuit components having an opening for entry of cooling air, a tube-mount having a'sleeve for receiving the cooling fins of said tube, means for supporting said tube-mount with said sleeve in position to receive air from said openingfor cooling of said tube fins and spaced from said opening to allow flow of incoming air toward the other circuit components, a vane mounted for response only to the air discharged from said sleeve, a switch for controlling supply of' current to said tube, and mechanical means coupling said vane to said switch for actuation thereof upon predetermined decreased flow of air from saidsleeve.

8. An arrangement for preventing overheating of high-frequency circuit components including an electronic tube which comprises a shield compartment for said circuit components having an opening for entry of cooling air, a tube-mount having a sleeve for receiving the finned anode of said tube, a vane movably supported by said tubemount to encircle the mounted tube between its finned anode and its glass envelope, mean for supporting said tube-mount with said sleeve in position to receive-air from said opening for cooling of the tube anode and envelope and spaced from said opening to allow flow of incoming air toward the other circuit components, a switch disposed externally of said compartment, and mechanical connecting means coupling said 'vane to said switch for actuation thereof in response to decreased flow of 'air from said sleeve.

9. Anarrangement for preventing overheating of an electronic tube comprising a tube-mount having a sleeve for receiving cooling fins of the tube, an air-flow vane pivotally supported by said tube-mount in the path of cooling airdischarged from said sleeve afterpassage over said cooling fins, a switch for controlling supply of current to sa-id'tubaand a rod suspended from said vane for actuation of said switch'by said vane in response to predetermined decreased discharge of air from said sleeve.

10. An arrangement for preventing overheating of an electronic tube comprising a tubemount for supporting the tube in position with its glass envelopeuppermost and with its finned anode in a sleeve of the mount, an air-flow vane pivotally supported from said mount to encircle the tube above the sleeve and below the tube envelope, a rod pivotally suspended from said vane, and aswitch member engaged by said rod for actuation in response to movement of said vane.

llJAn arrangement for preventing overheating of an electronic tube comprising 'a tubemount having a sleeve for receiving cooling fins of the tube, and an air-flow device comprising a bracket detachably secured to said mount, a member pivotally mounted on said bracket, and a vane detachably secured to said member normally positioned thereby in the path of cooling air discharged from said sleeve and removable from said member for replacement of the tube.

12. An arrangement for preventing overheating of an electronic tube comprising a tubemount for supporting the tube with its glass envelope uppermost and with its finned anode in a sleeve of the mount, and an air-flow device comprising a bracket detachably secured to said mount, a member pivotally mounted on said bracket, and a vane attached to said member to encircle'the tube for response to flowof air from said sleeve toward the glass envelope.

13. An arrangement for preventing overheating of an electronic tube comprising a tubemount for supporting the tube with its glass envelope uppermost and with its finned anode in a sleeve of the mount, an air-flow device detachable as a unit from the mount comprising a bracket disengageably secured to the mount, structure pivotally supported by said mount and including an air-flow vane encircling the mounted tube for response to flow from said sleeve toward the tube envelope, and rod structure pivotally suspended from said pivotally supported structure, and a switch unit mounted for actuation of its contact-operating member by said rod.

14. An arrangement for preventing overheating of an electronic tube comprising a tube mount having a sleeve for receiving the finned anode of said tube, a base structure having an opening for discharge of air, shock-mount means for resiliently supporting said tube-mount with said sleeve in position to receive air from said opening for cooling of the tube anode, and an air-flow device comprising a vane movably supported upon said tubemount for response to flow of air from said sleeve, a switch unit mounted upon said base structure, and an actuating rod for said switch unit freely suspended from said device and coupled to said vane thereof.

SHELDON V. JENNINGS.

'The following references are of record in the file of this patent: 

